[OSCOM] Kupu suddently stopped working

Hi,

Kupu suddenly stopped working while I did not change a single thing of my 
setup - this server has been running for over a year without any 
administration intervention. An error window appears with this text:
 
There was a problem initiaiting the drawers. Most likely the XSLT or XML files 
are not available. If this is not the Kupu demo version, check your files or 
the service that provide them (error: this.baseelement has no properties).


Zope 2.7.4, Python 2.3.4, Kupu 1.3.5

Which specific XSLT or XML files should I look for?

-- 
Milos Prudek